I have been enjoying my crossfired RX480's since launch. I just updated to 16.8.3 AFTER DDU'ing the previous drivers. Nowe i experience GPU CORE Clock that drops down to almost zero with crossfire activated. I've already DDU'd them and reloaded them. No change. It does it in Deus ex Mankind divided and Battlefield 1, with the new profiles provided by AMD.
When it does it, the system pauses for a second...complete pause. Screen, mouse and keyboard unresponsive when it does it. The PSU is a RM850X that is two weeks old, a brand new MSI 990fxa motherboard wirh the newest bios, plenty of airflow in case and the cards are not thermal throttling. Fx8370 not overclocked and in fine operating temps, not overheating. Cards are not overclocked or under volted in any way.Power efficiency is OFF. Fan curve has been adjusted to 3000 min, to 5000 max to keep them cooler. Windows 10 pro 64 bit with the newest AMD drivers for Windows 10 64 bit.
Included is screenshot of it doing it. Both with GPU-Z and Wattman. (1 card is XFX 8GB Black edition Ref RX480 1328mhz stock, 1 is XFX RX480 8GB 1266mhz Ref Style Stock)
It doesn't seem to do it on single card so far....I'll double check again though